Move surface vertically until it meets another surface by snapping to that surface

Hope this makes sense. Imagine I have a polysurface (a cube) above another polysurface (a wider box below the cube) and I want to move the cube’s bottom surface vertically until it reaches the wider box top surface.

Currently I am sub-selecting the cube’s bottom surface, then activate move with vertical constraint. In this mode I can snap to any of the wider box points (thus snapping to its “z”) but how can I snap to that same “z” without snapping to those points? (i.e. by hovering the mouse over the surface’s “middle” instead of its points?


I like to use the SetPt (Set Point) command for this sort of thing.

It might be a slightly different workflow than what you’re looking for… but I find it very good, and would recommend you give a full try and see if it’s something you can include into your standard assortment of tricks.

It’s especially good when your trying to align multiple points (at different distances) to a common reference plane.

Often used in combination with the PointsOn command.

Alternative Option:

Maybe also experiment with the TAB key on your keyboard, as a means for Locking Direction so you can go and reference other areas of your model (without taking your active selection with you).

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Thanks for the suggestion. To understand it: you first turn PointsOn, then SetPT on the selected surface, choose only “Z”? Then you’ll need to hover to one of those shown points?

I use Rhino on Mac, and I’m not 100% sure I get all of the functionality that you will get with the SetPt tool (given that your on Windows).

I do usually turn on the points in advance… However, in some cases it’s not necessary to do that… and if I remembered what those occasions were, I wouldn’t hesitate to tell you about them.

For some of the Solid Object try turning on SolidPt and an alternative to PointsOn (which won’t work for polysurfaces, and solids).

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You can’t really snap to some arbitrary point in the “middle” of a surface. If you turn on “Snappy dragging” with the gumball, you can simply subselect the bottom surface and then with the arrow handle pull it down and snap to one of the wider box corner points.

Otherwise you could use Extrude surface to boundary and pick the top surface of the wider cube, then you could use MergeAllCoplanarFaces to fix the joints. That would only work for planar surfaces.

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Thanks for all the suggestions. I think the only way is to really hover to a point OR to an edge (with the NEAR snap on). The “z” will be picked in these cases. Don’t like to make direct comparisons, but I was asking this because I (long time ago) used to do this all the times in Sketchup.

but thanks for this info, how on earth did I not know this setting :slight_smile:

why do you need to target the middle of a surface rather than a corner point, edge whatever, which gives you the exact same result, also in matter of time? have you got some example where this would be helpful?

It’s because sometimes, in complex and narrow spaces (like narrow interior spaces) those points or edges are not visible. Then I have to change visual style, or hide objects or layers to be able to hover over them. It’s no deal breaker, but does add one more step to the process. Unless I am missing something!

yes that can be sometimes almost futile trying to snap to something in tight conditions.
isolate might help.

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yes, isolate is also very handy in these situations.